chanworks

So i tried to search this problem and didn't really find a solution.

In the morning when I start my car, the engine will idle at about 2000 rpm when i start it up. Then about 10 seconds later, it'll start to drop, and it'll drop to about 300 rpm and the car will shake violently like it's about to stall out... but it doesn't! just when the car is about to die, the rpm guage shoots back up to about 2000 rpm, and the car comes back to life. it does this for about 2 minutes until the car is warmed up. then it'll idle at about 1300-1500 until i start driving, and everything goes back to normal.

i can't figure out what this problem is, and it only happens overnight. when i park for work or school, i can leave the car for 6, even 8 hours at a time and it's fine. only overnight for some reason. any help???

it's a 1996 civic sedan (DX i believe) with a swapped d15 non-vtec engine. previous owner swapped it out.

Bradsma

Kinda of sounds like the problem I was having with my main relay. Maybe yours is on the way out. Not an expert but thought I'd share.

chris_v2

Sounds like a gummed up throttle body and/or idle air control valve.

tkjode

iTrader: (1)

I just got my IACV cleaned out (it was crudded right up), and tossed in a new NGK O2 sensor.... had a similar bogging problem, but only when the car was warmed up... fixed the issue like a charm.

+1 on IACV check cuz it takes 2 seconds

ol Dusty

iTrader: (2)

+1 to the IAC and or TB. not sure what d15 you have but if it's got a fast air idle valve that could also be a potential cause of your problem. less likely but still a point of interest is that you may have air in the coolant or a small vacuum leak. the last 2 are less likely because the fact that it's not constant.

jamie1985

as in another post, check this out....How to fix your idleing woes! FITV IACV - Honda-Tech

chanworks

thanks for all the advice. i flushed/bled my coolant system, and the problem seemed to have disappeared for now (maybe cuz it's warm out?) if it occurs again i will clean the iavc and see whats up.